S2 is false because, it is given high level language.. and this is not assembly language.. and compiler is sitting between them... So it is undecidable what corresponding assembly language the compiler will generate.. We don't know what optimization option will be used for compiling.. compiler may be smart enough, he may use dirty write concept to optimize the code.. So if we say it will ALWAYS improve the performance, we can not say it just by looking the high level language.. , isn't it?.. So so S2 is false..